Side pocket mandrel and method of construction

ABSTRACT

An improved side pocket mandrel having a body comprising a one-piece main body section in which a main bore and a receptacle bore extend longitudinally therein and an upper body section having space therein for operating a kickover tool, welded together with a circumferential weld. In another embodiment, the machined main body section is welded by circumferential welds between upper and lower body sections. Additional embodiments are further disclosed having means therein for orienting kickover tools which are run and manipulated by wire line or pump down techniques and also having deflectors therein for deflecting regular well tools back into the main passage when approaching the receptacle from above and yet guiding flow control devices into the receptacle when such device is moved laterally into alignment with the receptacle by a kickover tool. Some disclosed embodiments have check valve means controlling flow between the exterior and the interior thereof. 
     Methods for constructing such side pocket mandrels and methods of welding tubular members, such as body sections of such mandrels, together with circumferential welds are also disclosed.

This application for patent is a continuation-in-part of U.S.application Ser. No. 86,723, filed Oct. 22, 1979, now abandoned whichapplication is a continuation-in-part of U.S. application Ser. No.77,184 filed Sept. 20, 1979, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to gas lift apparatus and more particularly toside pocket mandrels for use in wells produced by gas lift techniquesand to methods of constructing side pocket mandrels.

2. Description of the Prior Art

Generally, side pocket mandrels have been constructed with elongatetubular bodies having a window in the side thereof and a side pocketreceptacle body welded in the window so that the receptacle bore ispositioned inside the mandrel for receiving flow control devices while aportion of the receptacle body is exposed through the window and isprovided with lateral communication ports for conducting fluid flowbetween the receptacle bore and the exterior of the mandrel. Suchconstruction requires welds in which at least a portion thereof extendslongitudinally of the mandrel. Examples of such construction areillustrated in U.S. Pat. Nos. 2,824,525, 2,948,341, 3,412,806,3,666,012, 2,942,671, 3,040,814, 3,606,393, 3,727,684, 3,741,299,3,827,489, 3,994,339, 4,106,563, 3,802,503, 3,827,490, 4,030,543,4,106,564, 3,807,498, Re. 29,870, 4,031,954, 4,135,576, 3,807,499,3,874,445, 4,034,806, 4,146,091.

Some side pocket mandrels have utilized circumferential butt welds intheir construction to join adjacent tubular members together. Examplesof such welds are seen in U.S. Pat. Nos. 3,788,397, 3,827,490,4,135,576, 4,146,091. But such circumferential welds are simply buttwelds which join adjacent tubular members in end-to-end relationship.

Some side pocket mandrels are provided with deflector means extendingabove the receptacle bore for deflecting ordinary well tools movingthrough the mandrel back into the main flow passage to avoid possibilityof lodging on or in the side pocket receptacle and yet permitting andeven guiding a flow control device into the receptacle, thusfacilitating its installation. Some of these deflectors are integralwith the receptacle body, and some are welded to the upper end thereof.Most of the deflectors which are thus attached to the receptacle bodytend to result in a longer window in which it is welded by a longerseam, this extra length being added to the longitudinal dimension of theseam.

Over the many years that such mandrels have been in use, many failureshave occurred. Most of these failures occurred at longitudinalstructural welds. Most of the weld failures occurred in the longitudinalportion of the seam. The term "structural weld," as used herein, denotesweld seams which form a structural part of the side pocket mandrels.These structural welds are subject to stresses created in the mandrelsas a result of forces applied thereto as a result of tensile, columnal,or torsional loads, and are subject to pressures inside and outside themandrels. Failure of such weld will at least cause a leak in themandrel. Thus, the term "structural weld" as used herein also includesplug welds.

Failure in such welds is more readily understood in mandrels which arenon-circular in cross section. Non-circular mandrels, which include theoval shaped and the flattened, appeared long ago, and for the last 10-15years a very high percentage of the mandrels in use are non-circular.These are desired over the circular ones because two such mandrels willfit side by side or can pass each other in a smaller well casing, otherthings being equal. Or, alternatively, larger non-circular mandrels canbe used in dual wells for some given casing sizes.

When side pocket mandrels, and especially non-circular ones, havinglongitudinal structural weld seams in the wall thereof, are subjected tohigh internal or external pressures, the lateral walls tend to expand orcollapse, as the case may be. This expansion or collapsing movement ofthe mandrel wall results in very high stress concentrations at thelongitudinal welds. It is extremely difficult, if not impossible, toobtain welds in such places that (1) do not have a notch at the innerside where the inner wall of the mandrel meets the outer wall of thereceptacle body, and (2) do have full weld penetration.

Therefore, longitudinal structural welds provide weak places in suchmandrels and are a source of early failure under severe or even ordinaryconditions.

Also, many side pocket mandrels have been equipped with deflectors whichhave been joined to the mandrel through use of plug welds. In a similarmanner, many mandrels have been equipped with orienting sleeves fororienting kickover tools, which sleeves have often been attached insidethe mandrel by plug welds. Plug welds, while often used in themanufacture of side pocket mandrels, seldom appear in patents. Whatappear to be plug welds appear in U.S. Pat. No. 3,827,490.

Plug welds have also caused many failures. Since such welds areaccomplished by welding a part such as a deflector or orienting sleeveto the inner wall through a hole in the mandrel wall, such holeresembles a window and at least a portion of the seam around the windowwill be longitudinal in direction relative to the mandrel. Thus, it isbelieved that failure occurs at a plug weld for the same reasons thatfailure occurs at a window. While the hole for the plug weld is smallerthan the window in the window weld, the notch effect at the weld issomewhat similar.

U.S. Pat. No. 3,606,393 shows a receptacle body which has been madeespecially heavy in an effort to strengthen the window area and reduceweld failure, the increased mass of the material in the receptacle bodybeing intended to prevent wrapping as a result of the welding, but thenotch effect is still attendant, together with wall flexure underpressure in burst or collapse, and failures still occur.

Warpage of the mandrel as a result of welding has also been a problem inthe manufacture of side pocket mandrels. This occurs, of course, becausethe hot weld metal shrinks upon cooling. Shrinkage is largely dependentupon the quantity of weld metal deposited. Thus, long axially extendingseams warp more than short ones. When these seams are not opposite oneanother but are closer to one side of the mandrel, as they generally arein the case of a lateral window, especially a long narrow window,warpage can be considerable.

The stresses induced into the mandrel body by shrinking weld seams canliterally destroy the mandrel, but these stresses can be relieved byhearing the entire mandrel in a process known as normalizing. Thisprocess does not, however, remove the warpage, and the mandrel must bestraightened by bending in a direction opposite that of the warp. Thisstraightening process leaves the mandrel, then, with certain residualstresses therein, but, comparatively speaking, it is operable and is farmore acceptable than before.

It should be understood that while a certain amount of stresses may beacceptable in a mandrel, it would be ideal to eliminate them entirelysince they tend to facilitate certain corrosion processes.

U.S. Pat. No. 3,086,593 to Chitwood shows a check valve disposed in theflow passage extending through a gas lift valve which is installed inthe offset receptacle of a side pocket mandrel to prevent back flowtherethrough. Such check valves have been in common use. Similar checkvalves have been incorporated in such devices which are check valves perse and are not gas lift valves. These valves, when removed from thereceptacle, leave the lateral ports thereof open for free movement offluids therethrough in either direction.

Prior art drawing, Drawing No. 211--134 of Otis Engineering Corporation,P.O. Box 34380, Dallas, Texas 75234, shows a check valve disposed in aflow passage which is in direct communication with the extreme lower endof the offset receptacle of a side pocket mandrel. This check valve isnot removable and, therefore, remains effective at all times, even whenthe receptacle bore is vacant, but this type of side pocket mandrel hasvery limited application because it is not compatible with conventionalgas lift valves. In this type of mandrel, the lower end of thereceptacle bore communicates with the exterior of the mandrel; inconventional mandrels, the lower end of the receptacle bore communicateswith the main bore of the mandrel. In conventional gas lift valves forside pocket mandrels, lift gas enters the side of the valve and exitsthrough its lower end into the lower portion of the receptacle bore. Inthe conventional side pocket mandrel, the receptacle bore is alwaysdrained and gas lift valves can be installed therein without difficulty.In mandrels where the lower end of the receptacle bore communicates withthe exterior of the mandrel and a check valve is disposed in suchcommunication passage, as in Otis Engineering Drawing No. 211--134mentioned above, liquids can collect in the receptacle bore and thecheck valve will prevent their being drained, and installation of gaslift valves or other devices may be difficult or impossible because ofsuch trapped liquids.

None of the prior art known to applicants shows a check valve in thelateral port of a side pocket mandrel, the lateral port being in directcommunication with the receptacle bore at a location intermediate itsends, that is, at its mid section where devices can seal both above andbelow such lateral port.

The present invention overcomes the problems and shortcomings discussedabove by providing side pocket mandrels and methods for theirconstruction in which longitudinal structural weld seams, includingwindow welds and plug welds, are eliminated entirely and warpage andstraightening are minimized while providing a product which isconstructed with ease and is stronger and less susceptible to failure.This invention also overcomes the check valve problem by providing checkvalve means in the lateral ports of the mandrels to control back flowthrough the lateral ports.

SUMMARY OF THE INVENTION

The present invention is directed to side pocket mandrels having meanson opposite ends thereof for connection into a string of well tubing andcomprising a one-piece machined main body section and an upper bodysection welded together by a circumferential weld, the main body sectionproviding a full opening main bore and a machined receptacle boreextending alongside thereof and the upper body section having a bellyproviding space above the receptacle bore for operation of a kickovertool, such mandrels being provided as desired with means for orientingand activating kickover tools and with deflector means for directingflow control devices into the receptacle bore and directing regular welltools into the main bore. The present invention is also directed tomethods of constructing such side pocket mandrels including the methodof welding their tubular body sections together, also to side pocketmandrels constructed by such methods, some such mandrels also beingprovided with check valve means for controlling flow through themandrels' lateral ports.

It is therefore one object of this invention to provide an improved sidepocket mandrel having a one-piece main body section in which a fullopening main bore extends therethrough and a receptacle bore is machinedtherein alongside the main bore.

Another object of this invention is to provide such a side pocketmandrel in which the main body section is provided with means forattachment to a well tubing and is welded by a circumferential weld toan upper body section also having means thereon for attachment to a welltubing.

Another object of this invention is to provide a side pocket mandrel ofthe character just described wherein an orienting sleeve is provided andis welded or brazed in position surrounding the main passage in themandrel, such welding being done by access through the upper open end ofthe mandrel, such brazing being done in a furnace.

Another object is to provide a side pocket mandrel of the character justdescribed werein orienting means is formed in the main bore integralwith the main body section.

Another object is to provide a side pocket mandrel of the characterdescribed wherein deflector means is welded to the inner wall of theupper body section before the main body section is welded thereto.

Another object of the invention is to provide an improved side pocketmandrel having a one-piece main body section in which a full openingmain bore extends therethrough and a receptacle bore is machined thereinalongside the main bore and upper and lower body sections are welded bycircumferential welds to the upper and lower ends of the main bodysection, and wherein the upper and lower body sections have means forattachment to a well tubing.

Another object is to provide a side pocket mandrel of the character justdescribed wherein an orienting sleeve is welded or brazed into the upperbody section, such welding being done by access through the upper openend of the mandrel, such brazing being done in a furnace.

Another object is to provide a side pocket mandrel of the characterdescribed in which an orienting sleeve is welded inside the lower bodysection, such welding being done through the open upper end of the lowerbody section before such section is welded to the main body section.

Another object of this invention is to provide a method of constructingan improved side pocket mandrel by forming a one-piece main body sectionby machining a full opening main bore therethrough, machining areceptacle bore in the main body alongside the main bore, and formingmeans on its lower end for attachment to a well tubing, forming an upperbody section with a main passage therethrough and a belly or spacetherein above said receptacle bore for operating a kickover tool andmeans on its upper end for attachment to a well tubing, and welding theupper body section to the main body section by a circumferential weld.

Another object is to provide a method of constructing a side pocketmandrel of the character just mentioned wherein the main body sectionhas its lower portion formed separately by forming a lower body sectionwith a main passage therethrough and means on its lower end forattachment to a well tubing, and said lower body section is welded tothe lower end of said main body section by a circumferential weld.

A further object is to provide a method of constructing an improved sidepocket mandrel of the character described wherein an orienting sleeve isformed with an orienting slot with a stop shoulder at the upper endthereof and with a guide surface below the slot and directed upwardlytoward the slot, and said orienting sleeve is inserted in the upperportion of said upper body section above said belly and welded thereinabout its upper edge or brazed, such welding being done through the openupper end of said upper body section, such brazing being done in afurnace.

Another object is to provide a method of constructing an improved sidepocket mandrel of the character described by forming an orienting sleevewith an orienting slot therein and with a guide surface below the slotand directed upwardly toward the slot, and inserting the orientingsleeve into the lower body section and welding it in position thereinsurrounding the main passage, such welding being done with accessthrough an open end, preferably the open end of said lower body sectionand before the lower body section is welded to the main body section.

A further object is to provide a method of constructing an improved sidepocket mandrel of the character described, which method includes formingdeflector means and welding said deflector means to the inner wall ofsaid upper body section in proper location to be positioned above thereceptacle bore to deflect regular well tools away from the receptacleand toward the main passage as they move downwardly therepast, suchnon-structural welding being done through the open lower end of theupper body section before it is welded to the main body section.

Another object is to provide side pocket mandrels of the characterdescribed hereinabove having check valve means for preventing back flowthrough its lateral port means even when the offset receptacle bore hasno flow control device disposed therein, said lateral port meansproviding communication between the exterior of the side pocket mandreland the receptacle bore intermediate its ends.

Another object is to provide cartridge-type check valve means for sidepocket mandrels which are economical to manufacture and easy to installand remove.

Another object is to provide an improved side pocket mandrel such asthat just described wherein the check valve means is readily convertedfrom "outflow" checking to "inflow" checking mode, and vice versa.

Another object is to provide a method of joining a pair of tubularmembers such as side pocket mandrel body sections in end-to-endrelationship by a circumferential weld which provides full penetration,superior strength, and which does not obstruct or restrict the bore ofsuch pair of tubular members as a result of such welding.

Other objects and advantages will become apparent from reading thedescription which follows and studying the accompanying drawingswherein:

BRIEF DESCRIPTION OF THE DRAWING

FIGS. 1-A and 1-B, taken together, form a longitudinal sectional view ofone of the preferred embodiments of this invention;

FIG. 2 is a cross-sectional view taken along line 2--2 of FIG. 1-B;

FIG. 3 is a cross-sectional view taken along line 3--3 of FIG. 1-B;

FIG. 4 is a side elevational view of the orienting sleeve used in theside pocket mandrel of FIGS. 1-A and 1-B;

FIG. 5 is a cross-sectional view taken along line 5--5 of FIG. 1-B;

FIG. 6 is a fragmentary longitudinal sectional view showing an alignmentring in place between faying surfaces formed on the ends of adjacentbody sections which are ready to be welded together;

FIG. 7 is a fragmentary view similar to FIG. 6 showing the body sectionsof FIG. 6 after having been welded together, the weld having been groundflush on its exterior surface, and showing that the aligning ring wasmelted during the welding process;

FIG. 8 is a fragmentary view similar to FIG. 6 showing faying surfacesformed on the ends of adjacent body sections mated and ready to bewelded together;

FIGS. 9-A and 9-B, taken together, form a longitudinal sectional view ofanother preferred embodiment of this invention;

FIGS. 10-A and 10-B, taken together, form a longitudinal sectional viewof another preferred embodiment of this invention;

FIG. 11 is a cross-sectional view taken along line 11--11 of FIG. 10-B;

FIGS. 12-A and 12-B, taken together, form a longitudinal sectional viewof yet another preferred embodiment of this invention;

FIG. 13 is a side elevational view of the orienting sleeve used in theside pocket mandrel of FIGS. 12-A and 12-B;

FIG. 14 is a cross-sectional view taken along line 14--14 of FIG. 12-B;

FIG. 15 is a cross-sectional view taken along line 15--15 of FIG. 12-B;

FIG. 16 is a schematical view showing a dual gas lift well installationutilizing side pocket mandrels of this invention with check valves;

FIG. 17 is an elevational view partly in longitudinal section showing aside pocket mandrel similar to the side pocket mandrel of FIGS. 12-A and12-B but equipped with check valves;

FIG. 18 is a cross-sectional view taken along line 18--18 of FIG. 17;

FIG. 19 is magnified view of a portion of FIG. 18 showing one of thecheck valves controlling one of the lateral ports of the side pocketmandrel;

FIG. 20 is a fragmentary side view showing a check valve in one of thelateral ports of the side pocket mandrel of FIG. 17;

FIG. 21 is an exploded view of the check valve assembly of FIG. 19;

FIG. 22 is a schematical view showing an injection well installationutilizing gas lift mandrels of this invention equipped with checkvalves;

FIGS. 23-A and 23-B together constitute an elevational view partly inlongitudinal section showing a side pocket mandrel similar to the sidepocket mandrel of FIGS. 9-A and 9-B but equipped with check valves;

FIG. 24 is a cross-sectional view taken along line 24--24 of FIG. 23-B;

FIG. 25 is a magnified view of a portion of FIG. 24 showing an alternateform of check valve assembly shown in position to block inflow into thereceptacle bore from exterior of the side pocket mandrel;

FIG. 26 is a view similar to FIG. 25 showing the check valve assemblyand backup disk inverted so that outflow from the receptacle bore of theside pocket mandrel is blocked;

FIG. 27 is a fragmentary longitudinal view similar to FIG. 8 showing analternate shape for the external weld recess;

FIG. 28 is a fragmentary longitudinal sectional view similar to FIG. 7showing approximately the way the joint of FIG. 8 or of FIG. 27 wouldappear after the tubular body sections are welded together and the weldsubsequently ground flush;

FIG. 29 is a fragmentary longitudinal sectional view showing a portionof a tubular member having faying surfaces formed thereon preparatory towelding to a mating tubular member;

FIG. 30 is a fragmentary view similar to FIG. 29 showing a portion of atubular member having modified faying surfaces formed thereon; and

FIG. 31 is a fragmentary view similar to FIG. 29 showing a portion of atubular member having further modified faying surfaces formed thereon.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIGS. 1-A through 5, it will be seen that the sidepocket mandrel of this invention is indicated generally by the numeral20.

The mandrel 20 comprises a machined main body section 20a and an upperbody section 20b permanently joined together by a circumferential weld21.

Threads 22 and 23 are provided on the upper and lower ends of mandrel 20for attachment to a string of well tubing.

Mandrel 20 is shown to have features which are well known such as a fullopening main passage 25 extending throughout its full length, throughwhich well tools may pass, a side pocket or belly 26 offset from themain passage 25 providing space for operation of a kickover tool (notshown), a receptacle bore 27 extending alongside the main bore 25 andopening upwardly into the belly 26 for receiving a flow control device(not shown), the receptacle bore 27 communicating at its lower end withthe main bore 25 through cross passage 28 and, intermediate its ends,communicating with the exterior of the mandrel through lateral ports 29.

Mandrel 20, as shown, is further provided with well-known orientingmeans such as orienting sleeve 31 having the usual orienting slot 32,with a stop shoulder 33 at the upper end thereof, and guide surface 34therebelow for orienting a conventional orienting type kickover tool(not shown) which is normally activated by means thereon engagingdownwardly facing shoulder 33 provided at or near the upper end of slot32. The passage through the orienting sleeve is full opening. Thus theguide surface 34 is outside the full open bore.

The mandrel is also provided with deflector means such as deflectors 35and 36 which guide flow control devices (not shown), lowered into themandrel through the well tubing (not shown) on a kickover tool (notshown), into the receptacle bore 27 but which will deflect other welltools, passing through the mandrel, into the main flow passage 25 in thewell-known manner.

The receptacle, the orienting sleeve and the deflectors, generallyspeaking, are well known in the industry.

As shown, the mandrel 20 is substantially oval in cross section, havingopposing flat sides 37 and 37a connecting spaced apart opposingsemi-circular sides 38 and 39, as clearly shown in FIG. 2. The mandrelcould, however, be of circular or other cross section, as desired, butthe oval shape permits such mandrels to be used in dual wells where themandrels may be disposed in side-by-side relationship or may be movedpast one another in casing of reasonable size. Thus the flattened, oroval, shape permits use of smaller diameter casing or larger diametertubing, other things being equal.

The main body section 20a of mandrel 20 is machined from an elongatesolid one-piece main body blank preferably of the desiredcross-sectional shape and preferably oval, as shown, but which could becircular or some other non-circular shape. The body blank could be aforging, a casting, or the like. The full opening main bore 41 ismachined the full length of the blank, as shown, and the receptacle bore27 is machined in the blank and extends downwardly alongside main bore41. The lower portion of receptacle bore 27 may be reduced as at 27a, asshown, or it could be of the same diameter as that of its upper portion.Lateral ports 29 are drilled from the exterior surface of the blank intothe receptacle bore as shown in FIGS. 1-B and 2 to interconnect thereceptacle bore 27 with the region exterior of the blank. If both theupper and lower portions of receptacle bore 27 are of equal diameter,the bore should be enlarged slightly in the region of lateral ports 29to provide relief therefor to provide proper flow passage from saidports 29 to the ports of a flow control device (not shown) which may bedisposed in the receptacle bore to control flow through the ports 29 andcross passage 28. Providing the stepped receptacle bore as shown isgenerally to be desired because it is easier and less costly to machine.

An internal annular recess 44 is formed in receptacle bore 27 near itsupper end providing a downwardly facing shoulder 45 which is engageableby a lock means on a flow control device (not shown) for anchoring suchdevice securely in the receptacle.

A milling tool (not shown) of a diameter slightly smaller than thediameter of the main bore 41 is moved into the lower end of bore 41 to alocation opposite the lower portion of the receptacle bore 27 and ismoved laterally toward the receptacle bore to form the cross passage 28,thus, providing fluid communication between the receptacle bore 27 andmain bore 41, as shown. It can readily be seen that main bore 41 cancommunicate with the region exterior of the main body through crosspassage 28, receptacle bore 27 and lateral ports 29.

Thread 23 is machined in the lower end of main bore 25 for connection toa string of well tubing (not shown).

The lower end of the main body blank is preferably reduced in externaldimension as at 47 concentric with thread 23 to facilitate use ofhandling tools, wrenches, or tongs which may be used in connecting themandrel to the tubing. At the same time that the blank is reduced insize as at 47, a guide surface 48 preferably is also formed as shown toguide the mandrel past obstructions in the well on its downward tripthereinto.

The upper end of the main body section 20a is prepared for welding tothe upper body section 20b by providing suitable faying surfaces thereonas shown in FIG. 6. The upper end of the body section 20a is carefullyfaced as at 51, generally chamfered exteriorly as at 52, and shallowlybored providing an internal annular recess 53 having a lower sidesurface 54 which is inclined inwardly and downwardly.

The term "full opening" as used herein to describe the main passagethrough a side pocket mandrel denotes that such main passage isapproximately as large as the flow passage through the tubing for whichthe mandrel is fitted and will pass all ordinary well tools normally runthrough that size tubing. For instance, in 23/8" nominal tubing theinternal diameter is 1.995 inches and the drift diameter is 1.901inches, while the full opening dimension used in the industry is 1.875inches or larger since a bore of 1.875 inches or larger in landingnipples, and the like, will pass all ordinary tools designed for use insuch well tubing. The main bores and main passages of the side pocketmandrels described herein, such as main bore 41 machined in main bodysection 20a, are described as full opening and have an inside diametergreater than the established minimum diameter for "full opening" and infact are larger than drift diameter and will pass tools as large asdrift diameter. Such bore may also be termed non-restricting.

Here it should be noted that U.S. Pat. No. 4,135,576 shows what appearsto be a one-piece machined main body welded by circumferential welds toan upper body section. It is made very plain in the specification andclear in the drawing that the main bore in the main body is sorestricted (that is, so much smaller than drift diameter of the tubingbore) that additional bypass passages are provided to permit larger flowrates otherwise made possible by the multiple flow control devicesdisposed in the multiple receptacle bores.

Further, it should be noted that U.S. Pat. No. 3,040,814 shows amachined main body section which is obviously made in two halves whichare subsequently welded together by longitudinal structural weldsalthough this is not discussed in the specification.

In U.S. Pat. No. 3,412,806, what appears to be a circumferential weld isshown in FIG. 35 which is a cross-sectional view taken along line 35--35of FIG. 12. It will be noted that, in FIG. 12, the weld is not purelycircumferential but contains portions which are longitudinal, appearingto comprise four longitudinal portions connected together by fourarcshaped portions.

If the one-piece main body blank, from which the main body section 20ais formed, is produced by casting, forging, or similar process, it neednot be solid since one or both of the main and receptacle bores may beprovided therein by such process. If so, such bores may need onlyminimal machining. The receptacle bore will surely require finishmachining, and the main bore may need finish machining also. If thecasting or forging is carefully done, the main bore may be acceptable ascast or forged without such finish machining, thus effecting a saving inthe cost of machining. This saving in the cost of machining may possiblybe more than offset by the higher cost of more accurate castings orforgings.

The upper body section 20b is constructed from a length of tubularmaterial preferably of the same cross-sectional shape as the main bodysection 20a. The mandrels illustrated in this application are shown tobe constructed of material whose cross section is oval with a pair ofopposing flat sides such as flat sides 37 and 37a (see FIGS. 2 and 5),but it should be understood that other shapes are also practical,especially round.

In forming the upper body section 20b, a length of oval tubing havingthe shape shown in FIG. 5 is heated at its upper end for a distance ofseveral inches and is reduced in size as by forging or other suitableprocess to provide an end portion 61 which is eccentric and cylindricaland has a main passage 62 therethrough which is coextensive with andforms a part of main passage 25 which passes through the full length ofthe mandrel.

The reduced upper end portion 61 of the upper body section 20b is turneddown to suitable outside diameter, preferably equal to the size of atubing coupling, the bore 62 is cleaned up to predetermined insidediameter, and thread 22 formed in the upper end thereof.

The lower end of the upper body section 20b is prepared for welding inthe same manner that the upper end of the main body section 20a wasprepared. Its lower end is carefully faced as at 71 (seen in FIG. 6),generously chamfered exteriorly as at 72, and shallowly bored, providinginternal annular recess 73 having an upper side surface 74 which isinclined upwardly and inwardly.

Before welding the two body section together, the deflectors 35 and 36are welded in place as shown. The deflector 35 is inserted in the lowerend of the upper body section 20b and located a predetermined distancefrom the lower end thereof and in proper alignment with the receptaclebore and then welded in such position by applying a non-structural weldbead 74 along two edges as shown or preferably along three edges. Thisweld has little penetration and its volume is small. Therefore, it willresult in negligible distortion.

It will be noticed that deflector 35 has an outwardly facing verticalside wall comprising both flat and curved surfaces, 76 and 77,respectively, which conform to the inner wall of the mandrel in thelocation where it is to be welded and, thus, not only fits well but iseasy to align with the receptacle bore for welding. The deflector'sinner wall is concave at 78 and has a vertical rib at 79 to provide aguideway for guiding well flow control devices into the receptacle bore41. The deflector is beveled downwardly and inwardly as at 80, relativeto the receptacle bore, to further aid in guiding devices into thereceptacle. In addition, the deflector 35 is beveled downwardly andinwardly as at 81, relative to the main passage 25, to deflect regularwell tools away from the receptacle bore 27 and toward main bore 41,such regular well tools being generally too large in diameter to passbetween the deflectors 35 and 36.

The other deflector 36, seen in FIG. 5, is a mirror image of deflector35 and is installed in the same manner and functions in exactly the sameway as does deflector 35, the pair of them cooperating to perform theirfunctions as outlined hereinabove.

Orienting means is provided in the mandrel in the form of an orientingsleeve 31, better seen in FIG. 4. The orienting sleeve 31 is cylindricaland is provided with an orienting slot 32 providing a downwardly facingshoulder 33 at its upper end. The shoulder 33 may entirely block the topof slot 32, or block it only partially, as shown. The orienting sleevehas a guide surface 34 below the slot 32 which is directed upwardlytoward the bottom of the slot, as shown.

The orienting sleeve 31 may be welded in place either before or afterthe upper and main body sections are welded together. The orientingsleeve 31 is inserted in the upper end of the upper body section andpositioned therein above the belly 26 with its orienting slot 32 facingin the opposite direction from the receptacle bore and with itsdownwardly facing shoulder 33 a predetermined distance above thedeflectors and/or receptacle bore.

It is well known in the industry that the location and orientation oforienting sleeves are dictated primarily by the particular kickovertools used in the particular side pocket mandrels and in accordance withthe type of selectivity employed in the system. The orienting sleeve 31in mandrel 20 can be oriented as desired and placed at the desireddistance above the deflectors and/or receptacle bore as desired,according to the kickover tool to be used with the mandrel.

In joining the upper and main body sections together, their fayingsurfaces are brought together and an alignment ring or weld ring 84 ispositioned so that the upper and lower sides of its external flange 85are in contact with the end faces 51 and 71 of the adjacent bodysections 20a and 20b. The inner side 84a of the alignment ring 84 ispreferably semicircular as shown. This ring is generally formed from awire of the desired cross section. This wire is then wound or bent toconform to the shape of the end faces of the mandrel body sections, thatis, circular, oval, or the like, shape. A slight gap (not shown) is leftbetween the ends of the alignment ring, enabling the ring to becompressed slightly for easy insertion into the shallow bore at the endof one of the body sections. Alignment rings are well known to steelfabricators.

With the body sections assembled as shown in FIG. 6, and with the mainpassage 25 through them aligned axially, the two body sections, togetherwith the aligning ring therebetween, are tack welded at spaced intervalsabout their periphery to hold them fast for further welding. Welding isthen performed in the well-known manner beginning at the aligning ringand continuing around the mandrel in successive passes until theexternal recess formed between the upper and lower chamfers 72 and 52 ofthe body sections is more than filled by the weld metal. In this weldingprocess, the aligning ring 84 is preferably melted, thus providingcomplete penetration of the weld and providing a joint with maximumstrength. The inner portion of the aligning ring 84, although havingbeen melted in the welding process, should retain its shape to someextent and form an internal ridge or bead approximately as shown in FIG.7, which bead should remain entirely within the recess defined by theannular inclined surfaces 54 and 74 so that it will not protrude intothe main passage 25 where it might interfere with the passage oroperation of well tools, and the like.

It will be noticed that the weld 21 is purely circumferential,encompassing the mandrel in a plane normal to its longitudinal axis, andthat it is located at the end of the one-piece main body section 20a sothat this main body section lends very significant support to themandrel, enabling it to withstand greater differential pressures bothfrom within and without. The web 90 left between and separating the mainbore 41 and the receptacle bore 27 is extremely effective instrengthening the mandrel, especially so in the direction in which suchstrength is most needed, that is, in a direction normal to the majoraxis of the oval tubing and normal to a plane passing through thecenters of the main and receptacle bores. Of course, this web adds muchstrength to the mandrel as just mentioned above whether the mandrel isoval, round, or otherwise, since whatever the shape, there would exist aweb between the main and receptacle bores.

It is readily understood that, since distortion is caused by shrinkageof the weld metal upon cooling, the circumferential weld at the junctureof the two body sections will have little distortion effect since thestresses induced by such weld are evenly distributed about the mandreland tend to balance out. These stresses can be relieved by a post-heator normalizing operation, and there should be little or no need forsubsequent straightening of the mandrel.

It is understood that other types of faying surfaces could be formed onthe ends of adjacent body sections preparatory to circumferentially buttwelding them together. The form illustrated in FIGS. 6 and 7 may bepreferred by some fabricators while others may prefer another form suchas that illustrated in FIG. 8. For high quality mandrels which will besubjected to considerable pressures and loads, it is highly desirable toobtain full penetration of the weld.

While many forms of faying surfaces may be found suitable, the formillustrated in FIG. 8 should be very desirable because it is verysimilar to the form shown in FIG. 6 and completely eliminates thealigning ring, and its attendant difficulty in assembling, whilepermitting full penetration welding. However, satisfactory welds may beaccomplished using faying surfaces such as those seen in FIGS. 27, 29,30, and 31.

Referring to FIG. 8 it will be seen that upper body section 20b' isprepared for welding very much as shown for upper body section 20b inFIG. 6. Its lower end is faced at 71a, externally chamfered at 72a, andshallowly bored providing internal annular recess 73a having a sidesurface 74a which converges upwardly and inwardly. The upper end of mainbody section 20a' is prepared to appear much like main body section 20ashown in FIG. 6 but with the aligning ring, as it were, made integralwith the body. The upper end of the main body 20a' is reduced in outsidedimensions as at 95 so that this reduced portion is received in theshallow bore or recess 73a of the upper body section and also providingan upwardly facing shoulder 96 which abuts the lower end face 71a of theupper body section, as shown in FIG. 8. The reduced portion 95 on theupper end of the main body section 20a' fits rather closely in the bore73a of the upper body section 20b' and maintains the thus engaged endsof these two body sections against lateral displacement to facilitatethe tack welding operation. The upper end of the main body section isalso generously chamfered at 97, as shown. The inner edge of the upperend of the main body section 20a' is rounded as at 98 to resemble theshape of the inner portion of the aligning ring 84 seen in FIG. 6. It isdesirable, but not necessary, to provide an internal annular recess 99in the main body section adjacent the rounded corner 98 to provide aninternal ridge 100 to more perfectly provide a shape resembling that ofan aligning ring formed integrally with the main body section. If therecess 99 is not provided, the main body section should be at leastbored for a short distance to provide a recess similar to recess 53, 54of FIG. 6 to contain the innermost portion of the weld so that this weldwill not obstruct the main passage 25 through the mandrel 20.

During the welding process, the ridge 98 is melted to become a part ofthe weld as shown in FIG. 28 and provide full penetration in the samemanner that the aligning ring 84 was melted to become a part of the weldas explained in connection with FIGS. 6 and 7.

The weld is completed as before by tack welding at spaced intervalsabout the mandrel and then making successive welding passes around themandrel until the recess defined by the chamfers 72a and 97 on the upperand main body sections is more than filled with weld metal. The excessweld metal is then ground off to provide a surface which is flush withthe exterior of the mandrel body as is clearly shown in FIG. 28.

A similar welded joint can be produced by preparing the ends of thetubular members to be connected approximately as shown in FIG. 27. Thisjoint resembles the joints shown both in FIG. 6 and FIG. 8. Its internalrecess 73a' and 99' plus the rounded internal bead or ridge 98' aresubstantially like those shown in FIG. 8 while the external chamfers 72'and 52' are substantially like chamfers 72 and 52 of FIG. 6 and form anexternal circumferential V-groove. This welded joint is completed asoutlined hereinabove by assembling, tack welding, depositing continuouswelds during which full penetration is accomplished, over-filling theexternal V-groove with successive weld passes, and then, if desired,grinding the weld flush with the exterior of the tubular members. Thecompleted welded joint would appear approximately like that shown inFIG. 7 or in FIG. 28.

Alternatively, good full-penetration welds can be accomplished with theend of one of the tubular members, such as member 20a of FIGS. 6 and 7or member 20a' of FIG. 8, prepared even as shown in FIG. 29, 30, or 31.

In FIG. 29 such tubular member is indicated by the letter M. It has beenprepared by counterboring as at CB and further prepared by facing theend of the member to provide a first planar surface P1 and reducing theoutside dimension as at D to provide a projection which would fitclosely but telescope readily into the counterbore of the mating tubularmember such as counterbore 73a of tubular body member 20b' of FIG. 8.The short projection P is surrounded by a second planar surface P2. Themember M has been chamfered generously at C, but preferably would bechamfered as shown in dotted lines as at Ca.

In similar manner the tubular member Ma seen in FIG. 30 has beenprepared in the same manner as was the tubular member M of FIG. 29, butadditionally has been beveled at B as shown, this bevel B substantiallyremoving the remaining portion of the first planar surface P1 (seen inFIG. 29).

The tubular member Mb has been prepared in a manner similar to that ofmember Ma of FIG. 30, but instead of being provided with the bevel B,the inner corner of the projection P (seen in FIG. 29) has been roundedas at R, this rounded surface substantially removing the remainingportion of the first planar surface P1 (seen in FIG. 29). The member Mbof FIG. 31 has been prepared much like member 20a' of FIG. 8, but is hasnot been provided with the recess 99.

Either of the members Ma or Mb can be chamfered as was member M at C(FIG. 29), but is preferably chamfered as at Ca (FIG. 29).

When member M, Ma, or Mb is mated with a tubular member such as bodymember 20b of FIGS. 6-7 or member 20b' of FIG. 8, and welded asdescribed hereinabove, the full-penetration weld would be similar tothat shown in section in FIG. 28.

In either case, whether the faying surfaces are formed as shown in FIG.6 (which requires an alignment ring), or as shown in FIG. 8, 27, 29, 30,or 31, which needs no alignment ring, full-penetration homogeneous weldscan be more readily achieved under oxygen-free conditions. Tests haveshown that the pair of tubular members should be filled with an inertgas at least during the root welding pass or passes. This inert gasdisplaces the oxygen-laden air from the bores of these assembled membersand prevents formation of scale on the inner surface of the weld, thuspermitting the molten weld metal to form a scale-free, homogeneous weldwhich forms a well-shaped relatively flat bead, somewhat as shown inFIG. 7 or 28, which does not protrude into the normal bore of thetubular members.

While several inert gases may be suitable for use as a backing gas insuch welding operations as just described, Argon gas has been found tobe excellent.

Welded joints such as those typified by the welded joints shown in FIGS.6-8 and 27-31 have been constructed, tested, sectioned and inspected andfound to have full penetration, excellent physical characteristics, andto be substantially distortion free and homogeneous.

Either of the welds illustrated and described herein are suitable notonly in joining body sections of side pocket mandrels but are alsosuitable for welding other tubular members together.

It will further be seen that the deflectors and the orienting sleeve arewelded internally of the mandrel with light low-penetration low-volumewelds which have negligible distortional effect on the mandrel. (Thedeflectors could be secured in place by brazing, if desired.)

It will further be seen that plug welds and longitudinally extendingwelds, which would tend to weaken the mandrel, are not used in theconstruction of the side pocket mandrel hereinabove described; that theonly weld of consequence so far as the structural and physical strength,and competence of the mandrel are concerned is the circumferential weldjoining adjacent body sections and that it is both strong and wellsupported; and that it is non-longitudinal, and of full penetration, andrelatively non-distorting (due to the stresses induced thereby beingbalanced), as before explained.

Side pocket mandrel 20, having an orienting sleeve in its upper end, aswell as such mandrel without an orienting sleeve, would find greatestutility in well installations where flow control devices used in theirreceptacle bores are installed and removed through use of kickover toolsrun into the wells and withdrawn therefrom on a conventional wireline.Side pocket mandrels having orienting means below the upper end of thereceptacle bore are generally for use in underwater well installationswhere kickover tools are run into and out of the wells through use ofpumpdown or through flow line (TFL) techniques. In pumpdown operations,tool strings are moved through tubing strings and flow lines by pumpingfluid whose pressure is applied to piston elements forming a part ofeach tool string. One such mandrel for use in pumpdown wells isillustrated in FIGS. 9-A and 9-B.

Referring now to FIGS. 9-A and 9-B, a second embodiment of thisinvention will be seen to be indicated by the numeral 120. The sidepocket mandrel 120 is similar to mandrel 20 in that it comprises amachined main body section 120a and an upper body secton 120b joinedtogether by a circumferential weld.

The main body section 120a is machined from an elongate one-piece bodyblank of desired cross-sectional shape as was the main body section 20aof FIG. 1-B. A full opening main bore 141 is machined longitudinallythrough the blank, and receptacle bore 127 having a reduced lowerportion 127a is machined alongside main bore 141, as shown. Lateralports 129 communicate the exterior of the mandrel with the receptaclebore 127 at a point immediately above reduced bore portion 127a, andcross passage 128 interconnects the lower end of the receptacle borewith the main bore 141.

Recess 141 formed near the upper end of receptacle bore 127 provides adownwardly facing shoulder 145 engageable by lock means on a flowcontrol device (not shown) to secure such device in the receptacle borewhere it will control flow through lateral ports 129.

The upper body section 120b is formed much like the upper body section20b of the side pocket mandrel 20, previously described. It is formed oftubular material, reduced at its upper end as at 161 and threaded as at122. It is provided near its upper end with stop shoulder means whichwill be later described. The mandrel 120 has a full opening main passage125 extending therethrough threaded at both ends as at 122 and 123 forconnection to a string of well tubing, the main passage being continuouswith the bore of the tubing when the mandrel is connected therein and isa part thereof.

Deflectors 135 are welded to the inner wall surface of the upper bodysection 120b in the proper position, as shown, to function exactly as inthe preceding embodiment 20.

The upper body section 120b is welded to the lower body section 120a inexactly the same manner that the upper and lower body sections 20b and20a were welded together to provide mandrel 20, as before explained.

Main body section 120a has a reduced portion 147 at its lower end whichis substantially the size of a tubing coupling and is provided with aninternal thread 123 for attachment to a tubing string. Thread 123 isformed in the lower end of main bore 141.

Orienting means is provided in the main body section. Although suchorienting means could be provided by an orienting sleeve welded orbrazed in place in main bore 141 somewhere below the upper end of thereceptacle bore, the lower body section as shown has orienting meansformed integrally with the body 120a as shown. To provide the orientingmeans shown in FIG. 9-B, the lower end of main bore 141 is enlarged asat 141a to provide a downwardly facing guide surface 134 shaped like theguide surface 34 of the orienting sleeve 31 previously described. Thisguide surface 134 is below orienting slot 132 and is directed upwardlytoward the lower end of the slot. The guide surface is outside the fullopen bore. The upper end of the slot 132 runs out into the main bore 141and does not provide a downwardly facing shoulder since such shoulder isnot required in order to operate pumpdown kickover tools used in thismandrel. However, such a shoulder could be provided if desired. Instead,a downwardly facing shoulder 190 for activating a pumpdown kickover toolis provided by ring 191 disposed in the upper end of the mandrel 120where it rests upon upwardly facing shoulder 192 formed in the upperbody section 120b and is welded in place by a weld 193, as shown, suchweld being applied through the open end of the upper body section. Thepassage through the ring 191 is full opening and the shoulder 190thereon is outside the full opening bore.

It should be noted here that U.S. Pat. Nos. 4,106,563 and 4,106,564disclose orienting means forged integrally with an upper sub which formsthe uppermost portion of the mandrel, being welded to the mandrel by acircumferential weld. The orienting means of mandrel 120 hereindescribed is formed integral with the main body section, is located atthe lower end of mandrel 120 and has no stop shoulder at the upper endof the orienting slot.

Side pocket mandrel 120 performs the same functions as does mandrel 20but is constructed slightly differently since it is for use inunderwater wells and requires use of a pumpdown kickover tool. This typeof mandrel is very useful in pumpdown operations in underwater wells.

Rather than forming the orienting guide surface 134 and slot 132integrally with the main body section as shown, an orienting sleevecould be welded or brazed in place therein to orient a kickover tool. Toaccomplish this, the main bore 141 is enlarged at its lower end as at141a for a sufficient distance to accommodate an orienting sleevesimilar to the orienting sleeve 31 of FIG. 4. It is preferable in thiscase to bevel the upper end of the counterbore 141a, and the upper outercorner of the orienting sleeve would likewise be suitably chamfered sothat a cam surface rather than a stop shoulder would be present at theupper end of the orienting slot. This orienting sleeve preferably wouldhave holes of suitable size formed in its wall for non-structural plugwelding of the sleeve in place in counterbore 141a. Such welding,carefully done, would not interfere with the passage of well toolsthrough the orienting sleeve and would leave the guide surface unmarredby welding.

The side pocket mandrel illustrated in FIGS. 10-A, 10-B, and 11represents another embodiment of this invention. This mandrel isindicated generally by the numeral 220 and comprises a main body section220a, upper body section 220b, and lower body section 220c which arecircumferentially welded together as shown.

The side pocket mandrel 220 has a full opening main passage 225extending therethrough threaded at its opposite ends as at 222 and 223for attachment to a string of well tubing, the main passage 225 beingcontinuous with the bore of the well tubing when the mandrel isconnected thereto and is a part thereof.

The main body section 220a is machined from an elongate one-piece blankin much the same manner that the main body sections 20a and 120a weremachined. A full opening main bore 241 is machined longitudinallythrough the blank and a receptacle bore 227 is machined alongside themain bore, as shown. This bore could, if desired, extend only part ofthe way through the blank, in which case the bore would likely besmaller in diameter in its lower portion (below the lateral ports, inwhich case a cross passage such as cross passage 28 of mandrel 20 wouldbe required), or it could extend through the blank from end to end. Itis preferable to have the receptacle bore pass completely through theblank, as shown in FIG. 10-B. Receptacle bore 227, as shown, is notreduced in size in its lower portion as was the receptacle bores 27 and127 of mandrels 20 and 120. Receptacle bore 227 is enlarged as at 227afrom a point above lateral port 229 to a point therebelow to provideadequate flow area in that region to permit unhampered flow betweenlateral ports 229 and a flow control device (not shown) which may bedisposed in the receptacle bore. An internal annular recess 244 ismachined in bore 227, near its upper end as shown, to provide adownwardly facing lock shoulder 245 which is engageable by lock means ona flow control device (not shown) to secure such device in position tocontrol flow through lateral ports 229 which communicate the receptaclebore with the exterior of the mandrel. The receptacle bore 227 and themain bore 241 through the blank communicate by way of their open lowerends which are in direct communication with the space inside the lowerbody section 220c immediately therebelow. The main body section has bothof its ends prepared, as desired, for later welding to the other bodysections.

The upper body section 220b is formed in the same manner as was theupper body section 20b of the first embodiment and would beinterchangeable therewith except for the fact that they are welded totheir respective main body sections. Their structure, functions, andcharacteristics are identical.

The upper body section is reduced at its upper end as at 261 above thebelly 226 to the same diameter as a tubing coupling, and this reducedportion has a bore 262 in which a conventional orienting sleeve 231 iswelded about its upper end, as before. Deflectors 235 are welded to theinner wall of the upper body section before this section is welded tothe main body section 220a as before explained.

The lower body section 220c of side pocket mandrel 220 is formed in thesame manner in which the upper body section 220b is formed. It is formedof the same tubular material used to form the upper body section. Thelower end of the lower body section 220c is reduced as at 247, isfinished to the same diameter as a tubing coupling, and bored andinternally threaded as at 223 for attachment to a tubing string. Thisthread is concentric about the axis of the main bore 225 which extendsthroughout the full length of the mandrel.

The upper end of the lower body section 220c is prepared as desired forwelding as before explained.

Mandrel 220 is assembled so that the faying surfaces on the upper andlower ends of main body section 220a are properly abutted with thefaying surfaces on the ends of the upper and lower body sections 220band 220c, respectively. Thus assembled and with the main passage 225through the three body sections aligned axially, the adjacent bodysections are circumferentially welded together in the aforesaid mannerto complete the mandrel 220. If desired, one of the end body sections(upper and lower) can be assembled and welded to the main body sectionbefore the other section is assembled and welded thereto.

It was shown that the upper and lower body sections 220b and 220c weremade of identical tubular material. For ease of manufacture and to avoidwastage, these upper and lower body sections can be formed from a singlepiece of tubular material by forging the upper reduced portion 261 onone end of the tubular piece and forging the lower reduced portion 247on the other end of the same tubular piece and in axial alignmenttherewith. These reduced portions are then cleaned up by facing theirends, turning the reduced portions to proper size and boring them todesired internal diameter to make certain that a full-size main passageextends the full length of the tubular piece. This piece is then cutinto two pieces, one of them being the upper body section and the otherpiece being the lower body section. In the same manner, two upper or twolower sections could be made and then cut apart. Making two such piecestogether is especially expedient and economical where the die forgingequipment cannot perform the required forging operations on short piecesbecause considerable length may be required for gripping purposes. Theshorter lower body section may be too short to forge on some equipment,so tubular material can be saved by forging the sections in pairs andcutting them apart later.

The side pocket mandrel 220 of FIGS. 10-A and 10-B, when furnished withor without the orienting sleeve 31, finds greatest utility in wellswhere flow control devices are to be inserted in or removed from thereceptacle bore 227 through use of suitable kickover tools lowered intothe well and manipulated by conventional wireline techniques.

The side pocket mandrel illustrated in FIGS. 12-A and 12-B representsanother preferred embodiment of this invention and is seen to beindicated generally by the numeral 320. It is very similar to the sidepocket mandrel of FIGS. 10-A and 10-B, except that it has its orientingsleeve in its lower end and a tripping ring in its upper end and is,therefore, for use primarily in wells such as underwater wells whereflow control devices are inserted in and removed from the side pocketmandrel through use of a pumpdown kickover tool pumped into the well asa part of a pumpdown tool string.

Side pocket mandrel 320 comprises a main body section 320a which may beidentical to the main body section 220a of the mandrel 220, and an upperbody section 320b which may be identical to the upper body section 120bof mandrel 120, and a lower body section 320c which is much like thelower body section 220c with the exception of the addition of anorienting sleeve.

The main body section 320a is machined from an elongate one-piece bodyblank as was main body section 220a described earlier. It has a fullopening main bore 341 and a receptacle bore 327 extending alongsidethereof. Main bore 341 forms a part of and is continuous with mainpassage 325 which extends throughout the full length of the mandrel.Receptacle bore 327 is enlarged at 327a in the region of the lateralports 327 which communicate the receptacle bore 327 with the exterior ofthe mandrel. Near its upper end, receptacle bore 327 is enlarged as at344 to provide a downwardly facing shoulder 345 engageable by lock meanson a flow control device (not shown) to lock such device in thereceptacle bore in position to control flow through the lateral ports329.

Both the upper and lower ends of main body section 320a are prepared inthe desired manner for circumferentially welding to the other bodysections.

The upper body section 320b is the same as upper body section 120b ofmandrel 120 and performs exactly the same functions. It is provided withshoulder means in its reduced upper end portion 361 for activating apumpdown kickover tool. A cylindrical ring 391 having a full openingbore therethrough and a downwardly facing internal annular shoulder 390thereon is disposed on top of upwardly facing shoulder 392 formed in thereduced portion 361. The ring is welded or brazed in place as shown byweld 393 which is applied through the open end of the upper bodysection. This ring may be installed either before or after the sectionis circumferentially welded to the main body section.

The lower body section 320c is similar to lower body section 220c ofmandrel 220, but is modified by providing an orienting sleeve thereinfor orienting a pumpdown type kickover tool generally used in pumpdownor underwater wells.

The main bore of the lower body section is bored out a little deeperthan was the main bore of lower body 220c and provides an inclineddownwardly facing shoulder 320d which is engaged by the chamfered upperend 320e of orienting sleeve 331 disposed as shown in FIG. 12-B.

Orienting sleeve 331 is formed as shown in FIG. 13. It is cylindricalwith an orienting slot 332 open at both ends. It has an orienting guidesurface 334 below slot 332 and directed upwardly toward the slot in theusual manner. The sleeve is placed in the lower body section in positionsurrounding the main passage through the mandrel and is welded in placeas at 333 as clearly seen in FIG. 14. A series of holes 335 is providedin the sleeve on the side opposite the orienting slot to facilitate flowbetween the main bore and the lower end of the receptacle bore.

The side pocket mandrel 320 is of circumferentially welded constructionthe same as the mandrels described hereinabove. It serves the samefunctions as does the mandrel 12, both of them finding principal utilityin underwater wells in which operations are performed through use ofwell-known pumpdown techniques.

In some gas lift installations having side pocket mandrels serviced bymeans of pumpdown tools which must be moved through the well tubing bycirculation of liquids such as water, salt water, or oil, problems arisewhen the circulation path becomes short circuited because of one or morevacant side pocket receptacles. This can, for instance, happen veryreadily in dual wells such as that illustrated in FIG. 16.

In FIG. 16, the well installation 400 is equipped with casing 401penetrating upper and lower producing formations 402 and 403,respectively, which communicate with the casing bore 404 throughperforations 405 and 406, respectively.

Long and short tubing strings 411 and 412, respectively, are disposedwithin the casing, the long string 411 terminating adjacent the lowerzone 403 and its bore 414 communicating therewith through perforations406 while the short string 412 has its lower end disposed adjacent theupper zone and its bore 415 communicating therewith through perforations405.

The upper ends of the long and short tubing strings 411 and 412 areprovided with valves 417 and 418, respectively, at their upper endswhich are connected to flow lines 419 and 420, respectively.

A single well packer 422 is disposed between the upper and lower zones402 and 403 and seals the annulus between the tubing 411 and the casing401. A dual well packer is disposed a short distance above the upperzone 402 and seals the annulus between the two tubing strings (411 and412) and the casing 401. The thus isolated upper and lower zones 402 and403 communicate with the short and long tubing strings 412 and 411,respectively, and the flow streams from the two formations cannotcommingle.

The long tubing string 411 and the short tubing string 412 are fluidlyconnected through the lateral tubular connecting member 424 so thatliquids can be circulated down one tubing string, through the lateralconnection 424, and up the other tubing string to the surface in U-tubefashion. Of course, during such circulation operation, standing valves425 and 426 are disposed in the long and short tubing strings 411 and412, respectively, at a level below the lateral connection 424 toprevent pumping of liquids into either of the formations 402 and 403.

The long tubing string 411 is provided with one or more side pocketmandrels such as upper, intermediate, and lower side pocket mandrels430, 431, and 432, respectively, while the short tubing string 412 issimilarly provided with upper and lower side pocket mandrels 433 and434, respectively.

Using pumpdown tools and techniques, flow control devices in the sidepocket mandrels 430-434 can be serviced in the usual manner. However,since the location of pumpdown tools is determined principally byvolumetric measurements of the liquids pumped, and since a vacantreceptacle in a side pocket mandrel in either of the tubing stringscould allow some of the pumped liquid to pass outwardly from the welltubing through the lateral port(s) into the annulus, or permit lift gasfrom the annulus to enter through such port into the tubing, volumetricmeasurements of pumped liquids can be very inaccurate. Such inaccuracycan result in performing operations at the wrong location in the wellsuch as in the wrong side pocket mandrel or the like, and this can beboth costly and time consuming.

In gas lifting of such dual wells where at least one string of welltubing therein is equipped with side pocket mandrels of the typediscussed above, check valves are needed to prevent back flow, that is,out flow through the lateral ports. Check valves will thus permitmaintaining a fluid pressure in the circulating system at a valueexceeding the pressure in the annulus and thus maintain the check valvesclosed and preclude any flow through the lateral ports.

The side pocket mandrels 430-434 are each provided with a plurality oflaterals ports 430d, 431d, 432d, 433d, and 434d, respectively, and eachof these ports contains check valve means to prevent back flow oroutflow therethrough.

FIG. 17 shows a side pocket mandrel 430 which, except for the lateralport means, is shown to be exactly like side pocket mandrel 320 of FIGS.12-A and 12-B, but could be similar to any of the side pocket mandrelsshown in FIGS. 1-15.

The side pocket mandrel 430 of FIG. 17 is provided with a plurality oflateral port means 430d each of which includes check valve means moreclearly shown in FIG. 18. It is readily seen that lift gas from exteriorof the side pocket mandrel must pass through the lateral port means toenter the receptacle bore 427. It is preferable that the total flowcapacity of the plurality of lateral flow port means, with check valvestherein, equal or exceed the flow capacity through the gas lift valve orother flow control device disposed within the receptacle bore of theside pocket mandrel, this in keeping with good design practices.

The body 430a of mandrel 430 is provided with a plurality of lateralpassages 429 which communicate the exterior of the mandrel with thereceptacle bore 427. Passage 429 is enlarged as at 460 and furtherenlarged at 461 as shown to receive the check valve assembly.

The check valve assembly 462 includes a check valve cage 464, a ball465, and a check valve seat member 466 assembled as shown. Referring toFIG. 21, it will be seen that the check valve cage 464 has a flowpassage 467 therein which is about equal in size to that of passage 429in the mandrel body and which is enlarged at 468 providing an inclinedshoulder 469. The cage is provided with crossed slots 470a and 470b andthese slots extend upwardly in FIG. 21 for some distance above shoulder469. Thus, the crossed slots provide a plurality of dependent fingers471 having inwardly projecting bosses 471a. Enlarged bore 468 is onlyslightly larger than the diameter of ball but normally the ball is inengagement with the bosses 471a and the crossed slots provide ample flowpassage past the ball.

The check valve seat member 466 has a passage 466a therethroughapproximately equal in diameter to passage 429 in the mandrel andproviding a seat at 466d engageable by ball 465. Passage 466a isenlarged as at 466b to provide an abrupt shoulder 466c. Enlarged bore466b is sized to receive the upper end of the cage 464 which istelescoped thereinto as shown in FIG. 19.

The cage 464 may be bonded to the seat member 466 with the ball 465inside, if desired. The check valve parts may be formed of any suitablematerials. The ball is preferably formed of stainless steel. The cageand seat member may be made of steel, stainless steel, brass, or thelike metallic materials, but may preferably be formed of plasticmaterial. Thermoset plastics such as Phillips' RYTON (PolyphenyleneSulfide) or DuPont's VESPEL "SP-1" Polyimide Resin, for instance, arevery suitable materials from which to mold the cage and seat member, andespecially the seat member. These materials are suitable for injectionmolding, have adequate strength, and the seat will conform to the ballto make a good seal. (There is a second form of Polyphenylene Sulfidewhich is a thermoplastic suitable for compression molding. This materialmay be suitable for making check valve seats such as seat 466 but wouldnot be as suitable in production since injection molding has advantagesover compression molding.)

The check valve assembly 462 (composed of cage 464, ball 465, and seat466) is disposed in the lateral passage of the mandrel as shown in FIG.19 after a suitable seal ring such as o-ring 473 has been placed aboutthe cage. The check valve cage and seat are telescopingly assembled toone another and form a handy cartridge. If the cage and seat are formedof plastic material as mentioned above, bonding them together may bedesirable.

The cage portion of the check valve assembly 462 is disposed in enlargedbore portion 460 while the seat member 466 is disposed in furtherenlarged bore portion 461, the o-ring 473 being confined between theshoulder formed by the abrupt transition from bore 460 to bore 461 andthe end of the seat member, and it is also confined between the exteriorsurface of the cage and the wall of bore 461, thus to prevent flow offluids around the cage.

A washer-like back-up member 475 having a passage 475a therethroughequal in size to lateral passage 429 is installed after the check valveassembly 462, as shown, and supports the seat member, which may beformed of a relatively yieldable, non-metallic material, against highinternal pressures pressing the ball 465 against the seat withconsiderable force.

A retaining ring such as snap ring 476 is disposed in annular recess 477to retain the check valve mechanism in place as shown in FIG. 19. Whenthe ball 465 is "on seat" as shown, outflow cannot take place fromreceptacle bore 427 to the exterior of the mandrel since the ball closespassage 466a of the seat. Flow from exterior of the mandrel to thereceptacle bore 427 may take place readily since such inflow will movethe ball 465 to an "off seat" position permitting flow to take placethrough the seat passage 466a. Even if the ball is in engagement withthe internal bosses 471a of cage fingers 471, fluids may flow freelyaround the ball, pass through slots 470a and 470b and flow back intolateral passage 429 and thereafter enter the receptacle bore.

Provision of check valves in side pocket mandrels as just describedmakes it possible in a system such as that illustrated in FIG. 16 tomaintain fluid pressures in the tubing strings in excess of thepressures in the annulus exterior thereof to maintain the check valvesin all of the mandrels closed and thus prevent transfer of fluidsbetween the tubing and casing. In this way, accurate volumetricmeasurements can be made of the liquids pumped, thus permitting moreaccurate determinations of the location of the pumpdown tool string atany given time.

It is possible to provide check valves similar to the check valveassembly 462 just described but which checks flow in the oppositedirection. Such a check valve prevents flow from exterior of the sidepocket mandrel into it receptacle bore.

FIG. 22 illustrates a system wherein such side pocket mandrels findutility. In FIG. 22 a well casing 500 is shown to penetrate threeunderground formations which are indicated by numerals 501, 502, and503, representing the upper, intermediate, and lower formationsrespectively. These formations communicate with the bore 504 of thecasing through perforations 505, 506, and 507, respectively. A tubingstring 508 is disposed in the casing 500 with its lower end adjacentlower formation. 503. A first well packer 509 seals between the tubingand casing and separates the lower formation from the intermediateformation. A second well packer 509a seals the annulus between thetubing and casing and separates the intermediate from the upperformation.

The tubing string 508 includes a first side pocket mandrel 510 disposedopposite the upper formation and a second such mandrel 511 disposedopposite the intermediate formation while a suitable landing nipple 512is disposed adjacent the lower formation.

Well tools (not shown) such as injection regulators or the like aredisposed in the receptacle bores of both mandrels 510 and 511 and alsoin the landing nipple 512.

Fluids injected into the well from the surface move downwardly throughthe tubing and are injected into the separate formations 501, 502,and/or 503 under control of the injection regulators or the like (notshown). Such fluids may be injected into the formations for the purposeof maintaining their pressures as in water drive or recycling projectsor they may be injected merely to dispose of such liquids. In eithercase the formation pressures may be considerable.

When one of the injection regulators (not shown) is removed from one ofthe side pocket mandrels 510 or 511, fluids from the correspondingformation may tend to flow into the tubing and perhaps from there intoone of the other formations. The reverse check valves in the lateralports of the mandrels, however, will prevent such occurence.

A side pocket mandrel having such reverse check valves is shown in FIG.23 and is indicated by the numeral 600. Mandrel 600 is very similar tothe mandrel 20 of FIGS 9-A and 9-B except for its lateral porting whichincludes check valves mounted therein and seen in the cross-sectionalview, FIG. 24. Mandrel 600 could be constructed like that of mandrel 430of FIG. 17, if desired, or like any of the others described hereinabove,since this mandrel can be used with wireline as well as with pumpdownequipment.

FIG. 25 is a magnified view showing one of the check valves of FIG. 24.In this view the check valve assembly 662 is shown in position forpreventing fluid flow from the exterior of the mandrel 600 into itsreceptacle bore 627. Mandrel body 600a is formed with a main bore 641and a receptacle bore 627. A lateral passage 629 communicates thereceptacle bore 627 with the region exterior of the mandrel.

Lateral passage 629 is enlarged at 630 to receive the check valveassembly 662, and this bore is provided with a suitable internal recess677 in which a retainer ring such as snap ring 676 is disposed to holdthe check valve assembly in place. A suitable back-up in the form of awasher-like disk 675 having a central aperture 675a which issubstantially equal in size to passage 629 is disposed between the checkvalve and the snap ring to lend support to the check valve cage 664which may be formed of plastic material.

Check valve assembly 662 is very similar to check valve assembly 462previously described. Check valve cage 664 is provided with a bore 668which is enlarged so at 669 and further enlarged at 669a to receive theseat member 666 and provides a shoulder 669b which stops the seat member666 in the proper position in the cage as shown. The cage is providedwith fingers 670b having internal bosses 671a like those of the checkvalve cage 464 previously decribed.

A ball 665 which may be exactly like ball 465, previously described, isdisposed inside the cage 664 before the seat member 666 is inserted inbore 669a of the cage and is preferably a close fit therein. It isshouldered against shoulder 669b. If desired, the seat 666 can be moresecurely attached to the cage 664. This is particularly desirable if thecage and seat are to be made of a non-metallic material such as moldedRYTON or VESPEL "SP-1" as mentioned hereinabove with respect to checkvalve assembly 462, in which case they are preferably bonded. In eithercase, the assembly forms a cartridge-like check valve device which iseasily handled.

A seal ring such as o-ring 663 is placed about the seat 666 as shown toseal between it and the mandrel body 600a.

It is clear that the check valve assembly 662 will permit outflow fromthe receptacle bore but will prevent inflow.

It is now obvious that the check valve assembly 662, shown in reversecheck position in FIG. 25, can be inverted or flopped end for endrelative to the position shown in FIG. 26, in which position it servesas a regulating check valve like that illustrated in FIG. 19 and willprevent outflow. Thus, the check valve assembly 662 can be easilychanged from the FIG. 25 position to the FIG. 26 position as required.This, then, has the advantage of stocking mandrels having lateral portscounterbored and recessed as shown in FIGS. 25 and 26 and stocking checkvalve assemblies such as the assembly 662. Mandrels can then be suppliedwith or without check valves, and with the check valves in the regularor reversed position. Further, mandrels used for one type ofinstallation can be readily converted for another type of installation.Further, replacement or inversion of the check valves can be readily andeasily accomplished in the field without necessity of sending themandrels to a shop or to the factory.

Either of the check valve assemblies 462 or 662 is readily andinexpensively producible in the cartridge-like form which may be termeda cartridge-type check valve. This is especially true where the cage andseat are injection molded of RYTON or VESPEL "SP-1" and then telescopedtogether (and even bonded) with the stainless steel ball enclosedtherein.

Thus, it has been shown that side pocket mandrels embodying thisinvention comprise a one-piece main body section having a side pocketreceptacle bore machined therein alongside the main bore and that anupper body section is welded to the upper end of the main body sectionby a circumferential weld, this upper body section having a bellytherein offset from the full opening main passage which extends straightthrough the mandrel from end to end and of which the main bore of themain body forms a part. It has been shown that the lower end of the mainbody section can be formed with means thereon for connection to a welltubing string and that it can alternatively be provided with a lowerbody section which is welded to the lower end thereof, adapting the mainbody for attachment to a well tubing string. Thus, the mandrels maycomprise two or three body sections.

Additionally, it has been shown that these mandrels utilize onlycircumferential welds in their structural design and that these weldsare strong, being able to withstand high differential pressures,internal or external, and further strengthened by the one-piece bodysection which is massive and which has a web between the main andreceptable bores. Also, the circumferential welds used in these mandrelscause little distortion since the stresses resulting therefrom aredistributed equally about the mandrel so that they are balanced and sothat little or no straightening of the mandrel is subsequently required.The circumferential welds are fullpenetration welds, and they do notrestrict or interfere with the flow passage through the mandrel. Itshould also be noted that these mandrels, while being stronger, are alsoeconomical to manufacture.

It has been shown that these mandrels may be provided with orientingmeans and/or deflector means, as desired, and that such means are weldedinside the mandrel without using plug welds which require that a hole bemade through the mandrel wall prepatory to such plug welding. Instead,the orienting means and deflector means are welded inside the mandrel byaccess through the end of the mandrel body, some such welding being donebefore the mandrel body sections are joined by circumferential welding,but some of which can be accomplished after assembling although this isnot preferable. The light welds used for attaching the orienting meansand the deflector means are shallow penetration welds and have littleaffect on the mandrel so far as distortion, stresses, and competence areconcerned.

It has also been shown that these mandrels may be provided with theorienting means in their upper or lower ends depending upon thetechniques to be used in installing and removing flow control devicesused therein. If wireline techniques are to be employed, the orientingsleeve will generally be placed in the upper end of the mandrel. Ifpumpdown (TFL) techniques are to be used, the orienting means will belocated below the upper end of the receptacle bore.

It should be understood that the main body section 120a, 220a, or 320aof side pocket mandrel 120, 220, or 320, respectively, like main bodysection 20a of side pocket mandrel 20, may be formed from a one-piecemain body blank which has been produced by casting, forging, or similarprocess. Main body blanks produced by such processes may be cast orforged with the main bore therein. This main bore may or may not requirefinish machining, depending on the quality of the casting or forging. Ineither case, the claims appended hereto anticipate such side pocketmandrels and their method of construction, and such mandrels and methodsfor their construction are understood to fall within the scope of theappended claims.

It has been shown, too, that check valves can be provided in the lateralports or passages of the side pocket mandrels discussed hereinabove forcontrolling fluid flow through the lateral ports; that the check valvescan be installed to check outflow or inverted, that is turnedend-for-end, to check inflow; that the check valve assemblies arereadily installed or removed in the field without expert or factory helpand, therefore, are readily changeable from inflow to outflow mode, orvice versa; that the check valves are readily and economicallyproducible in cartridge form by attaching the seat to the cage with theball trapped therebetween; that the seat and cage are ideally injectionmolded of suitable plastic material and assembled together to provide acartridge-type check valve; and that the invertible check valve assemblysimplifies manufacture, stocking, and inventory operations.

Further, it has been shown that full-penetration, homogeneous welds ofsuperior quality and strength for high-pressure service can be achievedby permanently joining together a pair of tubular members using themethods set forth hereinabove; and that superior side pocket mandrelscan be provided through use of the structures and methods ofconstruction and methods of welding set forth hereinabove.

It also has been shown that the orienting sleeves and trip rings can bewelded in place as described or secured in place by brazing such as iscommonly done in a furnace, an induction furnace, or the like, whichbrazing operations are well-known. It is even anticipated that thedeflectors might be secured in place by brazing if desired.

In either case, the term welding as applied to such orienting sleeves,trip rings, and deflectors includes brazing.

The foregoing description and drawings of the invention are explanatoryand illustrative thereof, and various changes in sizes, shapes,materials, and arrangements of parts, as well as certain details of theillustrated construction, may be made within the scope of the appendedclaims without departing from the true spirit of the invention.

What is claimed is: .[.1. A side pocket mandrel, comprising: tubingstring..]. .[.2. The side pocket mandrel of claim 1, including:orientingmeans in said mandrel above said belly and engageable by a kickover toolfor orienting said kickover tool relative to said receptacle bore forinserting a flow control device therein or removing such a devicetherefrom..]. .[.3. The side pocket mandrel of claim 1, including: a.orienting means in said mandrel below the upper end of said receptaclebore and engageable by a kickover tool for orienting said kickover toolrelative to said receptacle bore for inserting a flow control devicetherein or removing such a device therefrom; and b. shoulder means insaid mandrel above said belly and engageable by a kickover tool foractivating said kickover tool..]. .[.4. The side pocket mandrel of claim1, 2 or 3, including: deflector means in said belly of said mandrelengageable by regular well tools to deflect such tools into said mainbore and away from said receptacle bore..]. .[.5. The side pocketmandrel of claim 4, wherein said lateral port means communicating saidreceptacle bore with the exterior of said main body section includes: a.at least one lateral flow passage fluidly communicating the exterior ofsaid main body section with said receptacle bore intermediate its ends;and b. check valve means in said lateral flow passage permitting fluidflow therethrough in one direction and preventing fluid flowtherethrough in the opposite direction..]. .[.6. The side pocket mandrelof claim 5, wherein said check valve means includes: a. check valve seatmeans having a seat surface thereon surrounding said lateral flowpassage; b. a check valve closure member engageable with said seatsurface to prevent fluid flow through said lateral flow passage fromsaid receptacle bore to the exterior of said side pocket mandrel andmovable to a position of disengagement from said seat surface to permitfluid flow through said lateral flow passage in the opposite direction;and c. seal means engaged between said check valve seat means and saidmain body section to prevent leakage of fluids around said check valveseat means..]. .[.7. The side pocket mandrel of claim 5, wherein saidcheck valve means includes: a. check valve seat means having a seatsurface thereon surrounding said lateral flow passage; b. a check valveclosure member engageable with said seat surface to prevent fluid flowthrough said lateral flow passage from the exterior of said side pocketmandrel into said receptacle bore and movable to a position ofdisengagement from said seat surface to permit flow through said lateralflow passage in the other direction; and c. seal means engaged betweensaid check valve seat means and said main body section to preventleakage of fluids around said check valve seat means..]. .[.8. A sidepocket mandrel, comprising:a. an elongate one-piece main body sectionhavingi. a main bore extending longitudinally therethrough, said mainbore being full opening, ii. a machined receptacle bore thereinextending alongside and offset from said main bore and open at its upperend, iii. lateral port means in said main body section communicatingsaid receptacle bore with the exterior of said main body section, andiv. means providing fluid communicating between said main bore and saidreceptacle bore below the upper end thereof; b. an upper body sectionwelded to the upper end of said main body section by a circumferentialweld, said upper body section providingi. a main passage therethrough inalignment with the main bore of said main body section, ii. an offsetbelly therein in alignment with said receptacle bore providing space foroperating a kickover tool for inserting a flow control device in saidreceptacle, and iii. means for connecting the upper end of said upperbody section to a tubing string; and c. a lower body section welded tothe lower end of said main body section by a circumferential weld, saidlower body section providing means for connecting the lower end of saidlower body section to a tubing string..]. .[.9. The side pocket mandrelof claim 8, including: orienting means in said mandrel above said bellyand engageable by a kickover tool for orienting said kickover toolrelative to said receptacle bore for inserting a flow control devicetherein or removing such a device therefrom..]. .[.10. The side pocketmandrel of claim 8, including: a. orienting means in said lower bodysection engageable by a kickover tool for orienting said kickover toolrelative to said receptacle bore for inserting a flow control devicetherein or removing such a device therefrom; and b. shoulder means insaid mandrel above said belly and engageable by a kickover tool foractivating said kickover tool..]. .[.11. The side pocket mandrel ofclaim 8, 9, or 10, including: deflector means in said belly of saidmandrel engageable by regular well tools to deflect such tools into saidmain bore and away from said receptacle bore..]. .[.12. The side pocketmandrel of claim 11, wherein said lateral port means communicating saidreceptacle bore with the exterior of said main body section includes: a.at least one lateral flow passage fluidly communicating the exterior ofsaid main body section with said receptacle bore intermediate its ends;and b. check valve means in said lateral flow passage permitting fluidflow therethrough in one direction and preventing fluid flowtherethrough in the opposite direction..]. .[.13. The side pocketmandrel of claim 12, wherein said check valve means includes:a. checkvalve seat means having a seat surface thereon surrounding said lateralflow passage; b. a check valve closure member engageable with said seatsurface to prevent fluid flow through said lateral flow passage fromsaid receptacle bore to the exterior of said side pocket mandrel andmovable to a position of disengagement from said seat surface to permitfluid flow through said lateral flow passage in the opposite direction;and c. seal means engaged between said check valve seat means and saidmain body section to prevent leakage of fluids around said check valveseat means..]. .[.14. The side pocket mandrel of claim 12, wherein saidcheck valve means includes: a check valve seat means having a seatsurface thereon surrounding said lateral flow passage; b. a check valveclosure member engageable with said seat surface to prevent fluid flowthrough said lateral flow passage from the exterior of said side pocketmandrel into said receptacle bore and movable to a position ofdisengagement from said seat surface to permit flow through said lateralflow passage in the other direction; and c. seal means engaged betweensaid check valve seat means and said main body section to preventleakage of fluids around said check valve seat means..]. .[.15. A methodof constructing a side pocket mandrel, comprising: a. forming a mainbody section including the steps ofi. forming an elongate solid bodyblank, ii. forming a full opening main bore lengthwise therethrough,iii. machining a receptacle bore in said body blank extending alongsidesaid main bore, iv. providing at least one lateral flow passage in saidbody blank interconnecting said receptacle bore and the exterior of saidbody blank, v. providing means communicating said main bore with saidreceptacle bore below the upper end thereof, and vi. providing means onthe lower end of said body blank for attachment to a tubing string; b.forming an upper body section having a main passage therethrough and anoffset belly therein for operating a kickover tool and means thereon forconnecting said upper body section to a tubing string; and c. connectingsaid upper body section to said main body section by circumferentiallywelding the two sections together..]. .[.16. The method of claim 15,including the additional steps of: a. forming orienting means fororienting a kickover tool for inserting flow control means in saidreceptacle bore and for removing such control means therefrom; and b.welding said orienting means in said upper body section above said bellyin predetermined position relative to said receptacle bore..]. .[.17.The method of claim 15, wherein the steps of forming the main bodysection further include the step of forming orienting means in said mainbore for orienting a kickover tool relative to said receptacle bore, andsaid steps for forming said upper body section includes the steps offorming a ring providing a stop shoulder thereon, and welding said ringin said upper body section with said stop shoulder in predeterminedposition relative to said receptacle bore, said welding being performedthrough an open end of said upper body section..]. .[.18. The method ofclaim 15, 16, or 17, further including the steps of: a. formingdeflector means for deflecting regular well tools into said main bore ofsaid main body section and away from said receptacle bore; and b.welding said deflector means in said upper body section in predeterminedposition relative to said receptacle bore, said welding being performedthrough the open lower end of said upper body section before said upperbody section is welded to said main body section..]. .[.19. The methodof claim 18, wherein said at least one lateral flow passageinterconnects the exterior of the body blank with the receptacle bore ata location intermediate its ends, and further including the step of:mounting check valve means in each said lateral flow passage to permitfluid flow therethrough in one direction and to prevent fluid flowtherethrough in the opposite direction..]. .[.20. A method ofconstructing a side pocket mandrel, comprising: a. forming a main bodysection including the steps ofi. forming an elongate solid body blank,ii. forming a full opening main bore lengthwise therethrough, iii.machining a receptacle bore in said body blank extending alongside saidmain bore, iv. providing at least one lateral flow passage in said bodyblank interconnecting said receptacle bore and the exterior of said bodyblank and, v. providing means communicating said main bore with saidreceptacle bore below the upper end thereof; b. forming an upper bodysection having a main passage therethrough and an offset belly thereinfor operating a kickover tool and means thereon for connecting saidupper body section to a tubing string; c. forming a lower body sectionhaving a main passage therethrough and means thereon for connecting saidlower body section to a tubing string; and d. connecting said upper bodysection to the upper end of said body section and connecting said lowerbody section to the lower end of said main body section bycircumferentially welding the adjacent body sections together..]. .[.21.The method of claim 20, including the additional steps of: a. formingorienting means for orienting a kickover tool for inserting flow controlmeans in said receptacle bore and for removing such control meanstherefrom; and b. welding said orienting means in said upper bodysection above said belly in predetermined position relative to saidreceptacle bore..]. .[.22. The method of claim 20, including the stepsof: a. forming orienting sleeve means for orienting a kickover toolrelative to said receptacle bore for inserting a flow control devicetherein or removing such a device therefrom; b. welding said orientingsleeve means in said mandrel below the upper end of said receptacle boreand in predetermined position relative thereto; c. forming a ringproviding a stop shoulder thereon engageable by a kickover tool; and d.welding said ring in said upper body section above said belly with saidstop shoulder in predetermined position relative to said receptaclebore, said welding being performed through the open end of the uppertubing section..]. .[.23. The method of claim 20, 21, or 22, furtherincluding the steps of:a. forming deflector means for deflecting regularwell tools into said main bore of said main body section and away fromsaid receptacle bore; and b. welding said deflector means in said upperbody section in predetermined position relative to said receptacle bore,said welding being performed through the open lower end of said upperbody section before said upper body section is welded to said main bodysection..]. .[.24. The method of claim 23 wherein said at least onelateral flow passage interconnects the exterior of the body blank withthe receptacle bore at a location intermediate its ends, and furtherincluding the step of: mounting check valve means in each said lateralflow passage to permit fluid flow therethrough in one direction and toprevent fluid flow therethrough in the opposite direction..].
 25. Themethod of joining a pair of tubular members in coaxial relationship by acircumferential weld, comprising:a. facing the end of the first of saidpair of tubular members to provide a planar end surface normal to itslongitudinal axis; b. counterboring the faced end of said first memberto provide an internal recess terminating with a sloping surface spacedfrom said faced end and converging in the opposite direction therefrom;c. chamfering the faced end of said first member externally, saidchamfer leaving a narrow portion of said planar end surface to beabutted by a corresponding planar surface of the second of said pair oftubular members when mated therewith for welding; d. facing the end ofthe second of said pair of tubular members to provide a first planarsurface; e. reducing the outside dimension of said first planar surfaceto form a short extension on the end of said second tubular member and asecond planar surface surrounding said extension and being parallel tosaid first planar surface, said extension being dimensioned to fitrelatively closely in said counterbore of said first tubular member; f.counterboring the faced end of said second member to form an internalrecess terminating with a sloping surface spaced from said faced end andconverging in the opposite direction therefrom; g. chamfering the end ofsaid second member externally reducing the width of said second planarsurface, the dimensions of said second planar surface substantiallyequaling those of said planar surface remaining on said first tubularmember; h. mating said pair of tubular members with their planarsurfaces fully abutting one another, the chamfers of said pair oftubular members together forming an external recess with inwardlyconvergent walls extending about said pair of members; i. tack weldingthe mated tubular members together at spaced intervals thereabout; j.welding said pair of tubular members together by making a series ofwelding passes thereabout starting in the bottom of the external recessand continuing until the recess is more than filled with weld metal,said projection on said second tubular member being substantially meltedduring the welding operation, said weld leaving the bore of said pair oftubular members unrestricted thereby.
 26. The method of claim 25including the additional step of: chamfering the inner edge of saidsecond tubular member, substantially removing the remaining portion ofsaid first planar surface.
 27. The method of claim 25 including theadditional step of: rounding the inner edge of said second tubularmember, substantially removing the remaining portion of said firstplanar surface.
 28. The method of claim 25, 26, or 27, including thefurther step of removing the excess weld metal to a level flush with theexterior of said pair of tubular members.
 29. The method of claim 25,26, or 27 wherein said chamfers on said pair of tubular members are soshaped that said external recess formed thereby when said tubularmembers are assembled has a profile comprising convergent side wallsconnected to a substantially flat bottom by arcuate lines.
 30. Themethod of claim 29, including the further step of removing the excesswell metal to a level flush with the exterior of said pair of tubularmembers.
 31. A side pocket mandrel comprising a plurality of tubularbody sections joined together by one or more circumferential welds madein accordance with the method of claim 25, 26, or 27, one of saidtubular body sections being an elongate one-piece section having a mainbore extending therethrough and a receptacle bore extending alongsidesaid main bore.
 32. A side pocket mandrel comprising a plurality oftubular body sections joined together by one or more circumferentialwelds made in accordance with the method of claim 28, one of saidtubular body sections being an elongate one-piece section having a mainbore extending therethrough and a receptacle bore extending alongsidesaid main bore.
 33. A side pocket mandrel comprising a plurality oftubular body sections joined together by one or more circumferentialwelds made in accordance with the method of claim 29, one of saidtubular body sections being an alongate one-piece section having a mainbore extending therethrough and a receptacle bore extending alongsidesaid main bore. A side pocket mandrel comprising a plurality of tubularbody sections joined together by one or more circumferential welds madein accordance with the method of claim 30, one of said tubular bodysections being an alongate one-piece section having a main boreextending therethrough and a receptacle bore extending alongside saidmain bore.